title: Studies of platelets with heavy metal impregnation techniques.
abstract: Various methods of heavy metal impregnations were performed on human platelets. The optimal technique consisted of glutaraldehyde fixation, incubation in warm uranyl acetate at a pH of 3.5, followed by a double solution of lead and copper, and finally overnight immersion in cold osmium tetroxide. Semi-thin sections, viewed at 90 kV, revealed three types of platelets: (1) 'reticular' cells, with a prominent tubular network and very dark granules in a pale cytoplasm; (2) 'dark' cells, with an electron-dense cytoplasm; and (3) 'pale' cells, with microvesicles and non-staining granules. Pre-treatments with EGTA, aspirin and various platelet activators altered the appearances and proportions of the three cell types. A cell-partitioning two-phase polymer system showed that the sub-grouping is related to surface membrane properties, the cells retained in the top phase being exclusively type 2 'dark' cells. The changes in cell type distribution produced by activation show that metal impregnation may be a useful method for studying structure-function correlations in platelets.
mesh_terms: D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000648:ultrastructure*; D003300:Copper; D004533:Egtazic Acid / Q000494:pharmacology; D006801:Humans; D007202:Indicators and Reagents; D007854:Lead; D008854:Microscopy, Electron; D014501:Uranium
chemical_list: D007202:Indicators and Reagents; D007854:Lead; D014501:Uranium; D004533:Egtazic Acid; D003300:Copper; D001241:Aspirin